Answer:
12 i. The work done by Wale = 107.910 kJ
The work done by Lekan = 117.720 kJ
Total work done = 225.36 kJ
ii. Wale's power = 4.3164 kW
Lekan's power = 3.924 kW
Wale has more power and is more powerful than Lekan
13. 313.92 N
Explanation:
i. The work done, W = Force, F × Distance moved by the force, D
The given parameters are
The mass of Wale = 55 kg
The mass of Lekan = 60 kg
The acceleration due to gravity, g =9.81 m/s²
The motion force of Wale and Lekan are;
Motion force of Wale = 9.81 × 55 = 539.55 N
Motion force of Lekan = 9.81 × 60 = 588.6 N
The work done by Wale = 539.55 × 200 = 107910 J = 107.910 kJ
The work done by Lekan= 588.6 × 200 = 117720 J = 117.720 kJ
107910 + 117720 =225630 J = 225.36 kJ
ii. Power = Work done/time
Wale finished the race in 25 s, therefore, his power = 107910/25 = 4316.4 W
Lekan finished the race in 30 s, therefore, his power = 117720/30 = 3924 W
Wale has more power and is more powerful than Lekan
13. The velocity ratio = 5
V. R. = Distance moved by effort/(Distance moved by load)
Efficiency = 80%
Work done by effort = x
Work done by machine = Efficiency × Work done by effort = 0.8 × x
Distance moved by effort, E = V. R. × Distance moved by load, D = 5 × D
Work done by effort = Force × Distance moved = 200×9.81× E
Work done by effort = 1962×E = 1962×E = 1962×5×D
Work done by machine = 1962 × D, when D = 1, we have;
0.8 × 1962×1 = 1569.6 J
Work done by effort = Force × Distance moved
Work done by effort = Force × 5×D = Force × 5 (D = 1)
From the principle of conservation of energy, we have;
Energy is neither created nor destroyed
Therefore
Work done by effort = Force × 5 = 1569.6 J
Force = 1569.6 /5 = 313.92 N.
